This was a reply in another thread but thought it might be better served in its own thread. Houm_wa, thank you for always replying with advice when I post! Much appreciated.

So I have read the forums for weeks, downloaded and read the FSM, just cannot pinpoint the issue.

Where to begin lol...

So this is my first LR, got it a couple months ago. Well taken care of by single previous owner. According to him, bags were recently replaced, rebuilt compressor put in, new front and rear valve blocks. Has Johnson rods installed. Holds full height even if parked for a week. Compressor started acting up, made a terrible internal noise. PO gave me the old compressor that he had rebuilt, swapped that in and helped. Rebuilt one started having issues with Vehicle Raising Slowly, found crack in drier cap, replaced with metal one, much better.

Right rear height sensor was acting up, screen would show it drooped all the way down, but it was normal and Gap IID showed normal voltage on sensor too. Repeated issue a few times, so I replaced sensor, checked wiring condition and recalibrated...just this morning same issue, shows wheel all the way down, red suspension light. Error:

• C1A06-92 (AF) Rear right height sensor - Component failure - performance or incorrect operation
  ( on 29-05-2018 10:19:28 at 153835 mi )
  - Test Failed
  - Test Failed This Monitoring Cycle
  - Confirmed
  - Test Failed Since Last Clear
  - MIL Requested

Yesterday, took it to an offroad park to test things out...major issues, numerous faults. At one point, for no reason on level ground it went down to bumpstops.

Some questions that I cannot seem to find on forum searches and reading the technical manual for the EAS:

There are no valves on bags themselves right? All air in/out is controlled by front/rear valve block and center block near compressor right?
When offroad, and suspension is articulating, I hear air sounds "chhh, chhhh, chhh" as wheels go up and down. I am guessing it is normal letting bags compress/fill?
When suspension drops to bumpstops, all height sensors show Out of Range, and thus unable to bring it back up. Must use Gap to manually inflate each to get it back within range...this seems odd no?
How does system detect when hung up on something and thus "Extended Mode - Clear Obstacle"? From day one I get this from time to time just on the road at a stop light. System manual does not define how it detects this.
When compressor is running, gallery pressure goes to about 250PSI (cannot recall off hand exact, might be more or less) as soon as compressor stops, pressure drops to about 45psi and then over the course of an hour or so drops to about 30psi. Is this normal?

Here are the other faults I am seeing:
C112F-72 (2E) Air spring valve - Mechanical failure - actuator is stuck open
Is there a way to decode from the fault code WHICH valve is stuck?
C1131-92 (2E) Air supply - Component failure - performance or incorrect operation
I assume this is the compressor? I
C1130-7A (2E) Air spring air supply - Mechanical failure - fluid leak or seal failure
C1A20-64 (AF) Pressure increases too slow when filling reservoir - Algorithm based failure - signal plausibility failure
C1A13-64 (2E) Pressure does not decrease when venting gallery - Algorithm based failure - signal plausibility failure

I'm somewhat at a loss here. I read and read about all the errors but am not figuring out what the culprit is.

Any ideas greatly appreciated!

 

You have rods, so going totally out of range will happen as you hit the bumps, the sensors are WAY past what should be the stop point.

There should be no sound during articulation. At least mine make no noises. The air will pass spring to spring through the proportioning valves, but that should not be noticeable.

The system monitors sensors position and galley air pressure. But when it comes to an issue causing extended, I am pretty sure its noticing an abnormal change in heigh sensors relative to others or a reading that shows no change when expected. That is, when lowering they should all change at the same rate - not necessarily be at the same height, mind you. So if its lowering and detects the rear dropping but not the front at the same rate, it thinks you are hung up on something. Of really if it wants to lower and NO corner responds at an expected rate (like hung up on snow), it goes into extended. Keep in mind, you can request more height by putting your foot on the brakes pedal and holding the raise suspension switch for three seconds. The vehicle will chime once. But the issue should not happen at a stop light.

Reading over your faults, it seems like the compressor is not working right. And not venting right. This could be line damage or the compressor itself. I think you need to start with basics and look for leaks. If its not dropping when sitting, your valve blocks are likely in good shape. But there are three and the middle one, near the compressor, could be an issue. I would start at the center valve and the tank. Remove the compressor covers to listen. Spray down with soapy water to help detect leaks. Also look at the compressor dryer. Two lines come out, one with an orange fitting the other blue. Between where the lines are on the dryer cap, a crack can form causing leakage.

 

 

Are you certain that when cross-linked both actually change air volume and that its not just one doing all the lifting? Because I would *think* that when cross-linked the valve to both bags would have to be open and thus indicated both bag valves work. Then again, I am not exactly sure how the valve block is designed/works.

I wish the rear block was not so hard to get at as one could simply swap with the front for trouble-shooting purposes.

 

 

I'm confused by what you mean when you say "when cross-linked" but at this point I think you are making this more difficult than it needs to be.

Take off the Johnson Rods, re-calibrate, get help from GAP Diagnostics. ....then you're done. Not sure why you bought parts already when there are free actions yet to take in your troubleshooting journey.

Is your compressor a Hitachi or an AMK?

 

That is definitely the plan. Going to pull rods and recalibrate. However, I cannot calibrate until I replace the valve block because the right rear is inoperative so I have no way to raise and lower it to the required measurement spec during calibration. The only way the right rear moves is if the crosslink valve opens thus allowing air in and out technically through the left rear valve channel. I can hear the valve click but not as forceful as the others and no air in or out so I am fairly certain that valve is stuck shut.

I am still running Hitachi compressor (rebuilt OEM). Eventually I want to just throw in a brand new one and am leaning toward sticking with Hitachi vs AMK.

I am a bit stumped why I am also getting the same error for the right rear sensor which is brand new. Values all look good. I am hoping maybe the stuck valve is related.

 

Okay, I get it now, about the valve block....why stick with Hitachi? Just curious.

 

No real reason other than I believe the main push to AMK was due to the Hitachi plant going down after that Tsunami...not necessarily a better solution. Since Hitachi's are available again I just figured go that route.

I'm also interested in the Lucky8 "HD Hitachi Style" unit...they claim they made improvements upon the original design but I am weary to go non-OEM with the compressor since I have heard many 3rd party units are terrible.

 

Oh there were plenty of claims that the AMK units were better, even if that wasn't the main reason to go away from Hitachi. Most of that data is anecdotal, however.

Only real issue with the AMK is the fitment of sliders.